Due to the recent commercial development of single photon tracers for functional brain imaging, the diagnosis of certain brain disorders with clinical EGT (emission computed tomography) is already a reality in many community hospitals. However, the currently available single photon emission computed tomography (SPECT) systems do not have adequate resolution and sensitivity to fully exploit these radiopharmaceutical advances. The future importance of SPECT Imaging derives from its affordable cost and its increasing potential for functional imaging. SPECT can build on the vast knowledge base and the many diagnostic techniques developed by PET research to benefit the general public with widely accessible techniques. In order for SPECT to assume this important role, practical imaging systems characterized by high performance, specifically high resolution, will have to be developed. The goal of the proposed research is to develop a novel high performance SPECT system for clinical brain imaging. The concept of this SPECT system is based on our previously reported single-slice design, which features a rotating collimator assembly and a stationary ring-detector system. The current proposal extends our SPECT imaging technique to the 3rd dimension. This involves a redesign of the detector and the collimator systems to provide full axial coverage for brain imaging. Extensive preliminary investigations have been performed using both software simulations and bench-top experiments to establish the feasibility of the new collimator and detector configurations. A table-top prototype system is currently being constructed to demonstrate the performance potential of our new designs. The next step is to build an imaging system which is sufficiently versatile for a wide variety of clinical applications. This proposal seeks support for the development and construction of a prototype clinical SPECT system and the research which relates to this development. The imaging performances of the prototype system will be characterized and optimized in the investigation.